<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        <div id="app">
            <h2>{{message}}</h2>
            <h2 v-once>{{message}}</h2>
        </div>
        <script src="../../js/vue.js"></script>
        <script>
          const app = new Vue({
                el: '#app',
                data: {
                    message: '你好呀'
                }
            }) 
        </script>
    </body>
</html>